292 DICECIOUS AND Chap. V'IL. 



year, or during the two previous years, produce a 

 single fruit. If these latter bushes and the more 

 fertile female ones were to supplant the others, the 

 spindle-tree would be as strictly dioecious in function 

 as any plant in the world. This case appears to me 

 very interesting, as showing how gradually an herma- 

 phrodite plant may be converted into a dioecious one.* 

 Seeing how general it is for organs which are 

 almost or quite functionless to be reduced in size, it is 

 remarkable that the pistils of the polleniferous plants 

 should equal or even exceed in length those of the 

 highly fertile female plants. This fact formerly led 

 me to suppose that the spindle-tree had once been 

 heterostyled ; the hermaphrodite and male plants hav- 

 ing been originally long-styled, with the pistils since 

 reduced in length, but with the stamens retaining 

 their former dimensions ; whilst the female plant had 

 been originally short-styled, with the pistil in its pre- 

 sent state, but with the stamens since greatly-reduced 

 and rendered rudimentary. A conversion of this kind 

 is at least possible, although it is the reverse of 

 that which appears actually to have occurred with 

 some Eubiaceous genera and JEgiphila ; for with these 

 plants the short-styled form has become the male, and 

 the long-styled the female. It is, however, a more 

 simple view that sufficient time has not elapsed for the 



♦ Aceording to Fritz Miiller separate from one another, so 



( Bot. Zeitung,' 1870, p. 151), a that, although their surfaces are 



CliamisBoa (Amaraiitliacese) in covered with fairly well-developed 



Southern Brazil is in nearly the papillae, they cannot be fertilised, 



same state as our Euoiiynms. The 'I'hebe latter plants do not com- 



ovulesareequally developed in the inoiily yield any fruit, and are 



two forms. In the female the pistil therefore in function males. Never- 



is perfect, whilst the antliers are theless, on one occasion Fritz 



entirely destitute of pollen. In MuUerfoundflowersof this kind In 



the polleniferous form, the pistil which the stigmas had separatee^ 



ij short and the stigmas never and they produced some fruit. 



